fish assignment

8/8/2019 Fish Assignment

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Freshwater Shrimp Production - Frequently asked questions

By Laura Tiu and Geoff Wallat, Ohio State University - This article provides answers to anumber of frequently asked questions regards the cultivation of freshwater prawns in ponds. Thearticle has a focus on Southern Ohio but is equally relevant to many other regions.

Freshwater shrimp culture has recently become increasingly popular in many temperate regionsin the United States. The freshwater shrimp, or more properly freshwater prawn, is a member of a large group of freshwater crustaceans found in many parts of the world.

What are freshwater shrimp?

Most aquaculture efforts have concentrated on the Giant Malaysian Prawn, Macrobrachiumrosenbergii, which is a native of southern Asia. Culture efforts in the U.S. were initiated inHawaii in the 1960s, South Carolina in the 1970s and Mississippi in the 1980s. Despitethese efforts, substantial concentrated production of this species has not developed.However, over the past five years, interest in production of this animal has again increased due to

increasing demand for shrimp products, reduced supplies of shrimp (especially large sizes), andincreases in production rates for prawns based on new management and production practices. Other factors producing increased interest in production include identified markets for live and fresh prawns ininland locations, the growing trend among consumers wanting to know how their food was produced andthe discovery that prawns actually grow more rapidly at cooler temperatures.

Research on temperate culture of freshwater shrimp in the U.S. was initiated at Kentucky State Universityin 1990 and the results have led to the establishment of several freshwater shrimp operations inKentucky, Tennessee and Indiana. During this time of development in other states, freshwater shrimpwere not cultured in Ohio because the Ohio Division of Natural Resources (ODNR) restricted their culture.In 2000, the Ohio Aquaculture Association (OAA) worked with the ODNR to reevaluate the species and itwas subsequently moved to the unrestricted aquaculture species list.

In 2001, several producers in Ohio raised the first crops of freshwater shrimp. Freshwater shrimp arebelieved to have great potential for diversification of Ohio farms. They have a short growing season (June1st-September 15th) that fits in well with other farm activities, require little labor (20 minutes/day feedingand one long harvest day), and occupy underutilized existing water resources.

What kind of pond do I need to grow freshwater shrimp?

Freshwater shrimp have been grown in earthen ponds as small as 1/10th of an acre to as large as 5+acres. The ponds must be free of any existing fish/amphibians/turtles or the shrimp juveniles becomeexpensive fish food. Ponds are built to be both drainable and seinable (long harvest net). Ponds built withinternal or external harvesting basins are easiest to harvest. Newly dug ponds typically have poor production for the first few years. Well-established ponds (2+ years of production) are able to supporthigher levels of supplemental food sources (algae, insect larvae, planktonic animals) as nutrients becomestored in the pond bottom soils. It is becoming apparent through research and on-farm demonstrationresults that the shrimp require these supplemental food sources in addition to the pelleted diets for maximum production. Future investigations on increased fertilizer applications in newer ponds tostimulate production of these additional food sources will be needed.

C an I grow freshwater shrimp in tanks?

Freshwater shrimp are not yet being produced economically in tanks, although several people are trying.The shrimp are extremely territorial and cannibalistic, resulting in poor survivals in tanks. We do notcurrently recommend this method of culture and dont have any information on it.


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What about water quality?

Water quality is very important in shrimp ponds. In order to maintain appropriate dissolved oxygen levels,the ponds should be aerated 24 hours a day, 7 days/week during the culture period. Other water qualityparameters, such as temperature, pH, alkalinity and hardness should also be monitored. Pond water pHlevels can be very critical to successful shrimp culture, as it has been demonstrated that pH>10 may

cause significant mortalities.

Where do I get the shrimp?

Shrimp juveniles are purchased from freshwater shrimp hatcheries for around 10 cents each. There arehatcheries in Kentucky, Tennessee, Texas and Mississippi. Cost per shrimp varies depending on number ordered and delivery method. Some hatcheries will deliver shrimp ordered in sufficient quantity whileothers are shipped via airplanes.

H ow many do I stock?

Stocking densities of 16,000 to 24,000 shrimp/acre are recommended depending on the size of shrimpdesired at harvest. Lower densities yield the largest shrimp.

What do I feed the shrimp?

Shrimp need a pelleted feed. Some farmers feed a sinking catfish feed. At the research center, we used acommercially available shrimp feed that was 38% protein. Shrimp were fed twice a day, but some farmersprefer to feed at dusk, since shrimp are nocturnal animals.

What is the potential profit?

B udgets developed at the University of Kentucky estimate profits of $2000.00 to $5000.00 per acre. Thisis based on costs associated with a one-acre pond. Growing shrimp in ponds smaller than one acrewould lead to different profit projections. Careful business planning is recommended, as with all

aquaculture enterprises. We have had some ponds with zero production resulting in losses.

H ow do I market the shrimp?

The shrimp must be sold live or whole on ice. One must be HACCP certified in order to process theshrimp to sell as tails only. The shrimp are sold live for $5.00-$10.00 per pound. Shrimp are sold atfestivals, farmers markets, pond-side, restaurants, ethnic markets and as bait. Shrimp farmers inKentucky have formed a co-op in an effort to develop larger shrimp markets. Researchers in Ohio areinvestigating the feasibility of developing some value-added products.

What kind of permit do I need to raise shrimp?

In Ohio, you must possess an aquaculture permit to raise freshwater shrimp for sale. Aquaculture permitsare $50.00 annually, renewable each January. Aquaculture permits are available from the OhioDepartment of Natural Resources, Division of Wildlife.

Is there information specific to Ohio?

A nine-pond freshwater shrimp demonstration project was conducted in Southern Ohio, summer 2002.Results from that study are available on the following website.http://southcenters.osu.edu/aqua/new.htm


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Where can I get more information on freshwater shrimp?

Information is available on-line. Freshwater Prawns: B iology and Life Historyhttp://aquanic.org/publicat/usda_rac/efs/srac/483fs.pdf

Freshwater Prawns: Pond Production and Growout

http://aquanic.org/publicat/usda_rac/efs/srac/484fs.pdf Kentucky State University Aquaculture Program: Freshwater Shrimp Video and Manualhttp://www.ksuaquaculture.org/index.htm

KSU festival marketing manual:http://www.ksuaquaculture.org/PDFs/Process%20&%20Market.pdf

The Use of Agricultural Limestone and Gypsum in Ponds.http://aquanic.org/publicat/state/ky/liming_wp.htm

Preparing Your Pond for Freshwater Shrimphttp://aquanic.org/newsltrs/state/kentucky/k02-6110.pdf

The U.S. Freshwater Prawn and Shrimp Growers Associationhttp://www.freshwaterprawn.org/index.html

Freshwater Shrimp Enterprise Cost and Return Estimates for Kentuckyhttp://www.uky.edu/Ag/AgEcon/pubs/ext_aec/aec_ext98-05.pdf

Freshwater Shrimp Consumer Taste Panelhttp://www.uky.edu/Ag/AgEcon/publications/ext2001-15a.pdf

Shrimp and Trout in Georgiahttp://www.cpes.peachnet.edu/adsreport/ADSReport2001_9.pdf

FAO global production of freshwater shrimp (long, but good)http://www.fao.org/documents/show_cdr.asp?url_file=/DOCREP/005/Y4100E/y4100e00.htm

Where can I get more information on other aquaculture topics?

The worlds best aquaculture site www.aquanic.org.

Where can I get information if Im not on-line?

The following two factsheets are available for purchase ($0.10/page) from the OSU South Centers. Theycan also be faxed at no charge.

1. Freshwater Prawns: B iology and Life History, 1996, 4 pages

2. Freshwater Prawns: Pond Production and Growout, 1996, 6 pages

S ource: Ohio S tate University - October 2004


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Another Production Methods for the Whiteleg Shrimp

The whiteleg shrimp is native to the Eastern Pacific coast from Sonora, Mexico in the North,through Central and South America as far South as Tumbes in Peru. This fact sheet produced bythe Food and Agriculture Organisation of the United Nations explains how the different systemsof Whiteleg Shrimp production work.

Production

Production Cycle


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Production cycle of Penaeus vannamei

Production System


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Seed supply

Captured wild seeds were used in Latin America for extensive pond culture of Penaeusvannamei until the late 1990s. Domestication and genetic selection programmes then providedmore consistent supplies of high quality, disease free and/or resistant PL, which were cultured in

hatcheries. Some were shipped to Hawaii in 1989, resulting in the production of SPF and SPR lines, leading to the industry in the United States of America and Asia.

B roodstock maturation, spawning and hatching

There are three sources for broodstock P. vannamei:

y Where they occur naturally, broodstock are sea-caught (usually at 1 year of age andweighing >40 g) and spawned.

y Cultured shrimp harvested from ponds (after 45 months at 1525 g), are on-grown for 23 months and then transferred to maturation facilities at >7 months of age when they

weigh 3035 g.y Purchased from tank-reared SPF/SPR broodstock from the United States of America, (at78 months of age and weighing 3040 g).

Broodstock are stocked in maturation tanks in dark rooms supplied with clean, filtered seawater.Feeds consist of a mixture of fresh and formulated broodstock feeds. One eyestalk from eachfemale is ablated, leading to repeated maturation and spawning. Females of 810 months of agereproduce effectively, whilst males peak at >10 months. Spawning rates of 515 percent/nightare achieved, depending upon broodstock source. Females are either spawned in communal or individual tanks (to avoid disease transmission). The following afternoon, the healthy nauplii areattracted by light, collected and rinsed with seawater. They are then disinfected with iodine

and/or formalin, rinsed again, counted and transferred to holding tanks or directly to larvalrearing tanks.

H atchery production

Hatchery systems range from specialized, small, unsophisticated, often inland, backyardhatcheries to large, sophisticated and environmentally controlled installations, together withmaturation units. Nauplii are stocked into flat, or preferably 'V' or 'U' shaped tanks with a volumeof 4100 m, made from concrete, fibreglass or other plastic lined material. The larvae are either cultured to PL1012 in a single larval rearing tank, or harvested at PL45 and transferred to flat-

bottomed raceways/tanks and reared to PL1030. Survival rates to PL1012 should average >60 percent. Water is exchanged regularly (at 10100 percent daily) to maintain good environmentalconditions. Feeding normally consists of live food (microalgae and A rtemia ), supplemented bymicro-encapsulated, liquid or dry formulated diets. From hatching, it takes about 21 days toreach harvest at PL12. Care is taken to reduce bacterial/pathogen contamination of the larvalfacilities using a combination of periodic dry-outs and disinfections, inlet water settlement,filtration and/or chlorination, disinfection of nauplii, water exchange and the use of antibiotics or (preferably) probiotics.


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N ursery

Most farming operations for P. vannamei do not use nurseries, but transport PL1012 at reducedtemperature either in plastic bags or oxygenated transportation tanks to the pond and introducethem directly. In some instances, nursery systems are used and comprise separate concrete

nursery tanks or earth ponds, or even net pens or cages located within production ponds. Suchnursery systems may be used for 15 weeks. Nurseries are useful in colder areas with limitedgrowing seasons, where PL are nursed to a larger size (0.20.5 g) in heated tanks/ponds, beforestocking into ponds. The use of super-intensive, temperature-controlled, greenhouse-enclosed,concrete or lined raceways have given good results in the United States of America.

O ngrowing techniques

Ongrowing techniques can be sub-divided into four main categories: extensive, semi-intensive,intensive and super-intensive, which represent low, medium, high and extremely high stockingdensities respectively.

Extensive

Commonly found in Latin American countries, extensive grow-out of P. vannamei is conductedin tidal areas where minimal or no water pumping or aeration is provided. Ponds are of irregular shape, usually 510 ha (up to 30 ha) and 0.71.2 m deep. Originally, wild seeds entering the

pond tidally through the gate, or purchased from collectors were used; since the 1980s hatcheryreared PL are stocked at 410/m. Shrimp feed mainly on natural foods enhanced by fertilization,and once-daily feeding with low protein formulated diets. Despite low stocking densities, smallshrimp of 1112 g are harvested in 45 months. The yield in these extensive systems, is 150500kg/ha/crop, with 12 crops per year.

S emi-intensive

Semi-intensive ponds (15 ha) are stocked with hatchery-produced seeds at 1030 PL/m; suchsystems are common in Latin America. Regular water exchange is by pumping, pond depth is1.01.2 m and aeration is at best minimal. The shrimp feed on natural foods enhanced by pondfertilization, supplemented by formulated diets 23 times daily. Production yields in semi-intensive ponds range from 5002 000 kg/ha/crop, with 2 crops per year.

Intensive

Intensive farms are commonly located in non-tidal areas where ponds can be completely drained,dried and prepared before each stocking, and are increasingly being located far from the sea incheaper, low salinity areas. This culture system is common in Asia and in some Latin Americanfarms that are trying to increase productivity. Ponds are often earthen, but liners are also used toreduce erosion and enhance water quality. Ponds are generally small (0.11.0 ha) and square or round. Water depth is usually >1.5 m. Stocking densities range from 60300 PL/m. Heavyaeration at 1 HP/400600 kg of harvested shrimp is necessary for water circulation andoxygenation. Feeding with artificial diets is carried out 45 times per day. FCRs are 1.41.8:1.


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Since the outbreak of viral syndromes, the use of domesticated disease free (SPF) and resistant(SPR) stocks, implementation of biosecurity measures and reduced water exchange systems have

become commonplace. However, feed, water exchange/quality, aeration and phytoplankton blooms require carefully monitoring and management. Production yields of 720 000 kg/ha/crop,

with 23 crops per year can be achieved, up to a maximum of 3035 000 kg/ha/crop.In the 'bacterial floc' system, the ponds (0.071.6 ha) are managed as highly aerated,recirculating, heterotrophic bacterial systems. Low protein feeds are fed 25 times per day, in aneffort to increase the C:N ratio to >10:1 and divert added nutrients though bacterial rather thanalgal pathways. Stocking at 80160 PL/m, the ponds become heterotrophic and flocs of bacteriaare formed, which are consumed by the shrimp, reducing dependence on high protein feeds andFCR and increasing cost efficiency. Such systems have realized productions of 850 000kg/ha/crop in Belize and Indonesia.

Sup er-intensive

Recent research conducted in the United States of America has focused on growing P. vannamei in super-intensive raceway systems enclosed in greenhouses, using no water exchange (only thereplacement of evaporation losses) or discharge, stocked with SPF PL. They are thus biosecure,eco-friendly, have a small ecological footprint and can produce cost-efficient, high qualityshrimp. Stocking 282 m raceways with 300450 0.52 g juveniles/m and ongrowing for 35months has realized production of 28 00068 000 kg/ha/crop at growth rates of 1.5 g/week,survivals of 5591 percent, mean weight of 1626 g and FCRs of 1.52.6:1.

Feed supply

P. vannamei are very efficient at utilizing the natural productivity of shrimp ponds, even under intensive culture conditions. Additionally, feed costs are generally less for P. vannamei than themore carnivorous P. monodon, due to their lower requirement for protein (1835 percentcompared to 3642 percent), especially where bacterial floc systems are used. Feed prices for P.vannamei range from USD 0.6/kg in Latin America and Thailand to USD 0.71.1/kg elsewherearound Asia; FCRs of 1.21.8:1 are generally obtained.

H arvesting techniques

Extensive and semi-intensive ponds are harvested by draining the pond at low tide through a bagnet installed in the outlet sluice gate. If the tide does not allow harvesting, the water can be

pumped out. In some larger farms, harvesting machines pump shrimp and water up to the pond bank where they are dewatered. Intensive ponds may be harvested similarly and small 26 manseine nets are dragged around the pond to corral shrimp to the side of the pond from where theyare removed by cast or dip net or perforated buckets.

Partial harvesting is common in Asian intensive culture after the first 3 months. In Thailand,artificial sluice gates are temporarily installed inside one corner of the pond to harvest closedsystem ponds. Shrimp are then trapped in nets attached to this temporary gate when the pond is


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pumped out.

In super-intensive systems, the shrimp are simply harvested with large scoop nets when requiredfor processing.

Handling and processing

If shrimp are sold directly to processing plants, specialized teams for harvesting and handling arecommonly used to maintain shrimp quality. After sorting, shrimp are washed, weighed andimmediately killed in iced water at 04 C. Often sodium metabisulphate is added to the chilledwater to prevent melanosis and red-head. Shrimp are then kept in ice in insulated containers andtransported by truck either to processing plants or domestic shrimp markets. In processing plants,shrimp are placed in iced bins and cleaned and sorted according to standard export sizes. Shrimpare processed, quickly frozen at -10 C and stored at -20 C for export by ship or air cargo. Dueto an increasing demand, no taxes and higher profit margins, many processing plants operatevalue-added product lines.

Production costs

Production costs vary depending on many factors. Operational costs for seed productionaverages USD 0.51.0/1 000 PL, whilst sales prices vary from USD 0.4/1 000 PL810 in Chinaand USD 1.01.2/1 000 PL12 in Ecuador to USD 1.5 3.0/1 000 PL12 around Asia. Lower feedcosts and higher intensity levels result in mean production costs for ongrowing of approximatelyUSD 2.53.0/kg for P. vannamei, compared to USD 3.04.0/kg for more extensive P. monodon culture.

July 2009

A n o t h e r

Production Methods for the Indian White Prawn


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The Indian white prawn inhabits the coasts of East Africa, South Africa, Madagascar, the Gulf,Pakistan, the Southwest and East coast of India, Bangladesh, Thailand, Malaysia, Philippines,Indonesia, Southern China and the Northern coast of Australia. Here, the Food and AgricultureOrganisation of the United Nations explains how the different systems of production work.

P. indicus is non-burrowing, active at both day and night, and prefers a sandy mud bottom. Adults are normally found at depths less than 30 m but have also been caughtfrom 90 m. The shrimp mature and breed mostly in marine habitats and spend the juvenile andsub-adult stages of 30 to 120 mm total length (TL) in coastal estuaries, backwaters or lagoons.Juveniles can tolerate a much wider range of salinity (5-40 per cent) than adults. On thesouthwest coast of India the juveniles support a good commercial fishery in the backwaters and

paddy fields.

Geographic variations in size at first maturity are evident and vary from 130 to 149 mm TL. P.indicus females are highly fecund, ranging from 68 000 to 1 254 200 eggs from females of 140-

200 mm TL. There are five stages in ovarian maturation: immature, early maturing, latematuring, mature and spent. P. indicus belongs to the closed thelycum group and mating takes place immediately after the females moult. During mating, which normally occurs at night, thesperm packs (spermatheca) are deposited by the hard-shelled male into the thelycum of thenewly moulted, soft-shelled female. The females carry the spermatheca during ovarianmaturation and the sperms are dispensed at the time of spawning.

Fertilization is external as the ripe ova released by the female become fertilized by the spermextruding simultaneously from the stored spermatheca in the thelycum. Depending upon thetemperature, hatching takes place within 8-12 hours after spawning. The nauplii are freeswimming and non-feeding and pass through six moults. The larvae further pass through

protozoea (3 stages), mysis (3 stages), and then to postlarvae, which resemble the adult shrimp.The postlarvae migrate into the estuaries, settle and feed on benthic detritus, polychaete wormsand small crustaceans, and remain there until they attain 110-120 mm TL. These sub-adults thenreturn to the sea and get recruited into the fishery.

Production

Production cycle


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I ndian white prawn production cycle


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Production Systems

Seed supply

In the traditional paddy-cum-filtration systems, juveniles congregating around the sluice gate are

allowed to enter into the extensive fields during high tide. Earlier, wild seeds were also caughtand sold to shrimp farmers. However, with the establishment of hatcheries and also due tooverfishing, the dependence on wild seeds has been reduced.

B roodstock

Shrimp spawners for breeding purposes can be sourced either from the shrimp fishing grounds or can be developed in captivity by induced maturation of the adult specimens brought from thewild (>145 mm TL) and maintained in broodstock holding tanks. When wild spawners are used,they are carefully transported to the hatchery and maintained in flow-through systems in order torecover from the stress. The females are transferred individually in 500-1 000 litre

cylindroconical fibreglass reinforced tanks containing microfiltered and sterilized seawater of 30-35 salinity and at pH 8.0-8.2. A temperature range of 27-31 C is ideal for spawning,which takes place during the night, following which the spawners are removed and transferred torematuration tanks.

The size of P. indicus used for broodstock development should preferably be above 145 mm TL(20 g) for females and 140 mm (17 g) for males. The specimens, after a prophylactic treatmentwith 100 ppm formalin for 30 minutes, are stocked at 4/m and at a sex ratio of 1:1 in 100 tonnescircular tanks with an in situ biological filter. The tanks are covered and kept in a dark room.Three tanks of the above size can meet the broodstock requirements of a hatchery of 18 millioncapacity. Shrimp are fed with intertidal oligochaetes and clam and squid meat daily. Female

eyestalks are unilaterally ablated by an electrocautery apparatus for endocrine stimulation.

Shrimp mature within 9-27 days after ablation and the interval between two consecutivespawnings may be 3-15 days. P. indicus also mature and spawn in captivity without eyestalk ablation by maintaining the pH between 8.0 and 8.2, light intensity below 500 lux and feedingwith oligochaetes and fresh clam meat. However, ablated females produce ten, eight and sixtimes as many spawns, eggs and nauplii, respectively, compared to unablated females.

Estimates of the total number of eggs spawned are made by sampling. The eggs are allowed tohatch in the same tank. After estimating the total number of nauplii hatched, they are collected,washed and stocked into larval rearing tanks. Small-scale hatcheries purchase the nauplii from

nauplii producing centres for further rearing to postlarvae because broodstock maturationfacilities require higher investments and infrastructure. Traders pack nauplii at a density of 20 000/litre; the technology to pack at a higher density of 100 000/litre has also been developed.

H atchery production

Smaller indoor tanks of 2-5 tonnes capacity are used for rearing larvae up to PL3-5. Nauplii arestocked at 75-100/litre and fed on a mixed culture of diatoms dominated by Chaetoceros spp. or


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Skeletonema spp. The concentration of diatoms in the larval rearing tanks is always maintainedabove 20 000 cells/ml. From second or third mysis stage onwards, larvae are also fed on an egg-

prawn-custard mixture with a 100-150 particle size, A rtemia nauplii or microparticulate feeds.Larval rearing trials without the inclusion of the expensive A rtemia nauplii have been successful

but higher survival is achieved when Artemia is fed.

N ursery

The postlarvae (PL5) from each larval rearing tank are transferred into a nursery tank of 10tonnes capacity for further rearing to PL20. From PL5 onwards, artificial diets are commonlyused to reduce water quality deterioration. At a stocking density of 75 nauplii/litre, survival isestimated to be 75 percent from nauplii to PL5 and 80 percent from PL5 to PL20. Twelve larvalcycles can be obtained in 8 months. PL20 postlarvae can be directly stocked into grow-out pondsfor farming.

O ngrowing techniques

The culture practices followed are traditional, extensive, modified extensive, semi-intensive or intensive. Traditional farming practices are still practiced in tidal ponds along the Southwestcoast of India. Commercial semi-intensive farming has been adopted in Middle Eastern and inthe Gulf countries. Semi-intensive farming of P. indicus in some parts of India has been replaced

by P. monodon , due to higher economic returns.

T raditional

This system of shrimp farming, which involves the trapping and holding of juvenile shrimp brought in by tidal water, is practiced in Bangladesh, India, Indonesia, Myanmar, the Philippines

and Vietnam. On the southwest coast of India, paddy fields ranging in size from 0.5 to 10 ha thatare subject to tidal influence are auto-stocked with wild seeds of mixed varieties of shrimp andfish during November to April. These fields are seasonally used for a single crop of paddy duringthe monsoon season (June- September). Very large fields with deeper areas ranging in size from2 to 75 ha, where paddy cultivation is impossible, are also used for shrimp filtration throughoutthe year. Shrimp feed on natural food in the ponds and shrimp production varies from 400 to 900kg/ha/yr. P. I ndicus forms 36-43 percent of the total yield of shrimp.

Modified extensive

Ponds of 1 to 2 ha in size are constructed with separate inlet and outlet facilities on elevated sitesto allow complete pond drainage. Ponds are fertilized with organic and inorganic fertilizers andseeds are stocked at the rate of 60 000-100 000/ha. The shrimp feed on natural foods enhanced

by pond fertilization, and supplemented by artificial diets. Water exchange of 10-15 percent iscarried out daily. A production of 1 000 to 2 500 kg/ha/crop is achieved in 3-4 months of culture.

Semi-intensive

Semi-intensive ponds are stocked with hatchery produced seeds at the rate of 20-25 PL/m.


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Water exchange is regularly carried out by pumping. 4-6 aerators/ha are used for maintainingdesired levels of dissolved oxygen. Production levels of 2 500 to 5 000 kg/ha/crop are achieved.

Intensive

Intensive farming of P. indicus was first introduced when commercial shrimp farming wasinitiated in the late 1980s. The adopted stocking density was 50-100 PL/m. Feeding withartificial diets was carried out 4-5 times/day. Heavy aeration and water exchange to minimizeenvironment deterioration was practiced. The production level achieved varied from 10 000 to20 000 kg/ha/yr, while one entrepreneur claimed a production of 12 000 kg/ha/crop on theSoutheast coast of India, This farming system is not in practice in India now. However, intensivesystems are used in Saudi Arabia; a private company there has reported a production of 13 500tonnes of P. indicus from a total pond area of 2 800 ha.

Feed supply

In India farmers use locally manufactured commercial shrimp feeds (not specifically designedfor this species) as well as imported feeds designed for Penaeus monodon . Some farmers preparetheir own feeds but these are qualitatively poor. The cost of imported feeds is generally higher.In Saudi Arabia, the National Prawn Company prepares feeds specifically for Penaeus indicus asit is exclusively culturing this species.

H arvesting techniques

In traditional farming, harvesting starts 2 months after stocking and is carried out from dusk todawn for 7-8 days around every full moon and new moon period. Close-meshed conical nets arefitted to the sluice gates during low tide to harvest the stock. Final harvesting from extensive

farming is carried out after 3-4 months of ongrowing. Water is drained out during low tide andfurther reduced by pumping, using mobile diesel-powered equipment. The remaining shrimp areharvested by cast netting. In modified extensive systems and semi-intensive systems, harvestingis carried out by complete draining of the pond, the shrimp escaping through the sluice gate

being collected by bag nets. The remaining stock is harvested by hand picking. In Saudi Arabia,mechanical harvesting techniques are employed.

H andling and processing

Shrimp are washed, cleaned and weighed immediately after harvesting, before transfer to icewater at 0 C. The rectangular crates in which they are placed are then transported to the

processing plants by insulated trucks. In the processing plants, the shrimp are cleaned and sortedinto various grades to suit export requirements. Depending on market requirements, shrimp may

be processed into several forms, such as simple block frozen, ready-to-eat, whole chilled, IQF,and cooked products, which are exported by container ship or air cargo. As part of the worldwidemarketing strategy, major processors and exporters have adopted HACCP and ISO qualitycontrol systems.

Production costs


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Production costs depend upon the site, the type of culture system, the scale of production, thenumber of production cycles per year, and the incidence of diseases, etc. The average seed

production cost in India in 2000 was estimated to be about US$ 1.6/1 000. The cost of adultshrimp produced in a modified extensive system was estimated in 1996 to be US$ 4.20/kg but, asthis species is no longer commercially reared in India (only extensively), no modern cost

estimates are available. The production costs for this species, as reared in Saudi Arabia, are notavailable.

A pril 2009

ANOTHER Can Rice-Fish Farming Provide Food Security in B angladesh?

Bangladesh is one of the poorest and most densely populated countries in theworld. More than 140 million people occupy the country's 144,000 km 2 of area,consuming rice and fish as staple foods, reports the Network of AquacultureCentres in Asia-Pacific.

Bangladeshi people are popularly referred to as "Macche-Bhate Bangali" or "fish and ricemakes a Bengali." Rice and fish have been an essential part of the life of Bangladeshi peoplefrom time immemorial. Rice farming is the single most important livelihood for a vastmajority of the rural poor. The annual rice production is estimated to be 26.53 million tons 1 ,while fish production is 2.32 million tons 2 . The demand for rice and fish is constantly rising,with the population increasing by more than three million people each year. However, theland available for rice and fish farming is not expanding. Nevertheless, fish farming in ricefields offers a solution to this problem, contributing to food production and incomegeneration.


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Photo: Silver carp is a common species for both farming systems.

The total area of rice fields in Bangladesh is about 10.14 million ha and there are a further2.83 million ha of seasonal rice fields where water remains for four to six months of theyear 3,4 . These inundated rice fields can play an important role in increasing fish productionthrough integration of aquaculture. There are several positive effects of fish farming in riceyields. Integrated rice-fish production can optimise resource use through thecomplementary utilisation of land and water 5 . Integration of fish with rice farming improvesdiversification, intensification, productivity and sustainability 6,7,8 . Rice-fish farming is alsobeing regarded as an important approach to integrated pest management (IPM).

The adoption of rice-fish farming in Bangladesh remains rather marginal to date due tosocioeconomic, environmental, technological and institutional constraints 9 . Traditionally wildfish have been harvested from rice fields. The green revolution of agriculture has become aconstraint for the development of rice-fish farming. With the introduction of high yielding

varieties (HYV) of rice, the pest control strategy has preferred chemical pesticides10,11

.Nevertheless, reducing pesticide has taken place through IPM. The introduction of IPM withfish farming in rice fields becoming popularity in many Asian countries, such as China,Philippines, Thailand and Vietnam 12 .

In order to increase food production, a small number of farmers were encouraged to take uprice-fish farming in Bangladesh. Nevertheless, a number of issues are important for rice-fishfarming including production technology, socioeconomic and environmental aspects. Thispaper highlights key issues for sustainable rice-fish farming, to meet challenges for foodsecurity for the people of Bangladesh.

Methodology

F ield research was conducted for a period of six months from December 2007 to May 2008.The research design included selection of the study area, identification of target groups andselection of research tools for data collection. The method of data collection depends uponthe nature, aim and objectives of the study. Selection of particular method depends onnature of the research problems, duration of fieldwork and distance of the research site. Inorder to assess the rice-fish farming systems relevant to farmers' concepts andunderstanding, a participatory research method was employed. The major advantage of thismethod is that its coverage is much wider. However, one of the major risks is that the


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investigation has to depend solely upon the memory of the respondents. This was, however,overcome by applying a combination of data collection methods.

F igure 1. Research Design for field survey of rice fish farming

The study was conducted in the Mymensingh area of north-central Bangladesh which is oneof the rice bowls of the country. Geographically Mymensingh has been identified as the mostimportant and promising area for rice-fish culture, because of favourable resources andclimatic conditions, such as the availability of low-lying agricultural land, warm climate,fertile soil, and cheap and abundant labour. Hydrological conditions are also favourable forrice-fish farming as this area is located within the monsoon tropics with an average annualrainfall of 2,500 mm 13 . Moreover, conditions are highly encouraging for the expansion of rice-fish farming as the quantity of fish seed produced has risen rapidly in recent years fromaround 70 private hatcheries. Nevertheless, a small number of farmers (around 100) areinvolved in rice-fish farming in Gauripur and Phulpur sub-districts. These farmers receivedtraining from the Mymensingh Aquaculture Extension Project, funded by DanishInternational Development Assistance. Gauripur and Phulpur sub-districts were thereforeselected for the study.

A combination of participatory, qualitative and quantitative methods was employed forprimary data collection. A total of 80 rice-fish farmers, 40 in each sub-district, were

interviewed at their houses and/or farm sites. The interviews, lasting about an hour,focused on rice-fish farming systems, culture practices, productivity and constraints of rice-fish farming. A Participatory Rural Appraisal tool - focus group discussion ( F GD) wasconducted with rice-fish and rice-only farmers to obtain qualitative information. F GDsessions were held in front of village shops, under large trees, in farmers' houses and onschool premises, where participants could sit, feel comfortable and were easily observed.F inally, cross-check interviews were conducted with district and sub-district fisheriesofficers, agricultural extension officers, school teachers, researchers, policy makers and


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relevant non-government organisation (NGO) workers. Data from questionnaire interviewswere analysed using Microsoft Excel software to produce descriptive statistics.

Farming systems

Photo: A typical rotational rice-fish farm, Bangladesh.

There are two types of rice-fish farming systems in the Mymensingh area depending on thesource of fish: culture and capture. In the capture system, wild fish enter the rice fieldsfrom adjacent floodplains during the monsoon and reproduce in inundated rice fields. On theother hand, rice fields are deliberately stocked with fish in the culture system. F ish farmingin rice fields can be broadly classified as concurrent (integrated) and rotational (alternate).In the concurrent system, rice and fish are grown together, while in the rotational systemthey are grown alternately. According to the survey, 54% of farmers practiced concurrentrice-fish farming and the rest (46%) cultured rotationally. In general, the concurrent rice-fish culture system is practiced in plain-lands and medium lowlands, while the rotationalsystem is performed in deeply flooded lowlands. The average farm size was found to be0.33 ha and 0.29 ha in the concurrent and rotational system, respectively.

Two types of rice crops are cultivated in the concurrent system: boro and aman. F armerscultivate boro rice during the dry season from January to April, and the monsoon season

aman rice during June to October. The aman rice culture takes place in either deep orflooded water conditions with fish, and with a fish culture period of around 4 months. In therotational system, farmers produce fish during the monsoon. F ish fingerlings are stocked inMay to June and are harvested primarily from November to December, a culture period of around 5 to 8 months. Rotational farmers avoid cultivation of aman rice with fish due tohigh water levels. On the other hand, farmers avoid fish culture with boro rice because of water scarcity and lower availability of fingerlings.

A wide range of fish species are cultured in rice fields. The selection of species depends onfarming systems. According to the survey, concurrent farmers mainly stocked common carp( Cyprinus carpio ), silver barb ( Barbonymus gonionotus ), Nile tilapia ( Oreochromis niloticus )and silver carp ( Hypophthalmichthys molitrix ). In rotational culture, on the other hand, themost common fish species were stocked catla ( Catla catla ), rohu ( Labeo rohita ), mrigal( Cirrhina cirrhosus ), silver carp ( H. molitrix ), grass carp ( Ctenopharyngodon idella ) andbighead carp ( Aristichthys nobilis ). The average annual stocking density of fingerlings were2,857 per ha in the concurrent system, while it was 4,917 per ha in the rotational system.The average size of fingerlings stocked varied between 4 and 8 cm in the concurrentsystem, and 6 to 10 cm in the rotational system.

Although small-scale fish farming in rice fields is an extensive aquaculture system that relieson the natural food (phytoplankton, zooplankton, periphyton, benthos), supplemental feedsare used by most respondents. In the concurrent system, farmers mainly use on-farm


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inputs, such as rice bran, wheat bran and mustard oilcake. On the other hand, a fewrotational farmers apply fishmeal and industrially manufactured pelleted feeds, in additionto on-farm inputs. F armers reported higher fish yields when feeding pelleted feed ratherthan on-farm inputs. The most common feeding frequency in the rotational system wasonce per day, while it was once or twice a week in the concurrent system. There was asubstantial difference in feeding rate among culture systems ( Table 1 ).

In order to increase rice and fish production, a variety of fertilisers such as urea, triplesuper phosphate (TSP) and muriate of potash (MP) are used by the farmers. The fertiliserquantity used is related to farming system ( Table 1 ). Concurrent farmers with two rice cropsused less fertilisers on an annual basis than did rotational farmers of one rice crop becausethe presence of fish increased soil fertility.

The average annual yield of rice was higher in concurrent farming compared to rotationalfarming, because of two rice crops. Table 1 shows that concurrent farmers had a higheraman rice yield than boro rice as the stocking of fish affected the aman rice yield positively.Nevertheless, boro rice yield was slightly higher in rotational farming than that of concurrent farming.

The average annual yield of fish reported by respondents was 259 kg/ha in concurrentfarming, while 1,108 kg/ha in rotational farming. The yield of fish was higher in rotationalfarming due to higher inputs of fish seed, feed and fertiliser. In addition, rotational farmersstocked larger fingerlings which could have a positive effect on survival and growth, andthus also the yield. Comparatively larger size fish was harvested in rotational farming due tolonger culture period.

Constraints and opportunities

I rrigation facilities can help to expand rice-fish farming, Bangladesh.

A number of constraints were reported by respondents for fish farming in rice fields,including lack of technical knowledge, natural disasters (flood, drought), high productioncosts and poor water quality. Regardless of farming systems, 42% of respondents identifiedlack of technical knowledge as their single most important constraint. The proportion of respondents identifying high production costs was 34%. Cost of fish farming in rice fieldswas reported to have increased significantly in recent years as a result of increased fishseed, feed, fertiliser and labour cost. The prices of both fish fry and feed have increaseddramatically since fish farming has become widespread in pond systems. Inadequatefinance can therefore be a significant constraint for fish farming in rice fields. Only 19% and5% of farmers identified flood and poor water quality to be the most important constraint,respectively. Preventing fish escape is very difficult during the flood, especially for smallfarmers who are reluctant to raise their low and narrow dikes. F armers also reported higherfish mortality occurred due to poor water quality as a result of water pollution, turbidity, low


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water levels and high water temperature. A few concurrent farmers noted that they hadhigh fish mortalities when their neighbours used pesticides indiscriminately.

It seems that rice-only farmers quite unwilling to switch to rice-fish farming due to lack of technical knowledge. F armers suggested that rice yields decrease due to space occupied byrefuge. In addition, farmers perceived that fish damage rice plants and pesticide use for rice

crops have negative impacts on fish production. Rice farmers are also reluctant to adoptrice-fish farming because of risks. It was found that better-off farmers are active in rice-fishfarming due to the taking risk as they described "there is no gain without risk."

In spite of several constraints, there are opportunities for rice-fish culture development inBangladesh. A SWOT (strengths, weaknesses, opportunities and threats) analysis wascarried out with farmers to identify for its sustainable development ( Table 2 ).

E nvironmental impacts

Rice-fish farming provides a sustainable alternative to rice monoculture, if farmers can takeadvantage of the natural productivity of the rice field ecosystem. Concurrent rice-fish

farming is ecologically sound and a good method of diversification where fish regeneratenitrogen and phosphorus to improve soil fertility. F ish release nutrients by stirring thesediments in rice fields. F oraging and movement of fish in rice fields causes the aeration of the water, which increases photosynthesis 5,14 . F ish also predate on flies, snails and insects,and can help to control malaria mosquitoes and water-borne diseases. On the other hand,rice fields offer fish planktonic, periphytic and benthic food. Shading by rice plants alsomaintains the water temperature favourable for fish during the summer 4,15 .

There is less use of fertilisers in concurrent rice-fish farming than rice monoculture. F ishwastes and the extra feed given to fish increase the amount of organic fertiliser in ricefields. Moreover, fish plays a significant role in controlling pests. They eat aquatic weedsand algae that carry diseases, act as hosts for pests and compete with rice for nutrients 12,16 .As a result, farmers need less fertiliser and pesticide leading to an improved environment.Thus, concurrent rice-fish farming is an organic method that maintains environmentalsustainability.

Many fish species prefer to reproduce in rice fields. Such natural aggregations of fish in ricefields inspire rice-fish farming for increased productivity. Rice-fish interaction can indeedincrease the rice yield. It has been reported that the cultivation of fish in rice fieldsincreases rice yields by 8 to 15% 17 .

Food security

The switch from rice monoculture to rice-fish farming is not merely a change in croppingsystem, more importantly it is a shift to production of a more balanced diet (i.e. rice andfish). Not only the adequate supply of carbohydrate, but also the supply of animal protein istherefore critical factor for the health and well-being of farming households. As a result of rice-fish farming, they are able to eat rice three times a day with fish. Rice fields arepotentially a source of protein for fish farming households. Among the farming systems,concurrent farmers had a significantly higher share of fresh fish in their diet than rotationalfarmers. In the rotational system, fish farming was a cash crop and thus 80% of theproduction was sold to local markets while the rest was consumed by the households. Incontrast, farmers of the concurrent system considered fish as a secondary farm product interms of economic return. Thus, 40% of the fish production was consumed by the


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households while the remaining was sold to local markets. It was found that households of farmers tend to eat small fish than sell them. In addition to animal protein, small fish are avaluable source of micronutrients, vitamins and minerals. Small fish has also particularimportance for the diets of children and lactating mothers to avoid child blindness andreduce infant mortality.

In order to meet the soaring demand for food, there is a need for increased food productionin Bangladesh. However, intensive rice monoculture cannot provide a sustainable foodsupply at the cost of long-term environmental sustainability12. Among the farming systems,concurrent rice-fish farming is the best in terms of food supply. Increased rice-fish farmingcould be a significant approach to increase food production. Concurrent rice-fish farmingcould provide social, economic and environmental benefits. This farming positively affectsthe rice yield and makes the rice field a more efficient ecosystem for environmentally soundproduction of rice and fish. Thus, concurrent rice-fish farming offers a sustainablealternative to rice monoculture.

If rice-fish farming is expanded to 2.83 million ha of seasonal floodplains in Bangladesh,food production would be significantly higher than its present level. Moreover, farmers'income and local food supply will increase substantially. It is therefore assumed thatintegrated rice-fish farming can ensure food security for the people of Bangladesh.

Sustainability

While there is a great potential for rice-fish farming, a number of issues were identifiedaffecting its sustainability including the lack of technical knowledge of farmers, highproduction costs and natural disasters (flood and drought). Moreover, rice-fish farmingtechnology has not yet contributed substantially to food security in Bangladesh due to itslow level of adoption. The lower levels of rice-fish farming adoption were found amongpoorer households. It seems that the benefits of rice-fish farming technology accumulate tobetter-off farmers unless institutional and organisational support is provided to resource-poor farmers. It is therefore worthwhile to find means of providing institutional andorganisational support to poorer farmers, in terms of training facilities and extensionservices for sustainable rice-fish farming. Training and technical support would help toimprove profitability and reduce risks. The provision of low-interest credit would also help toreduce risks for resource-poor farmers. F inally, a positive government policy can help topromote sustainable development of rice-fish farming throughout the country.

A cknowledgements

The study was supported through the Australian Government Endeavour ResearchF ellowship. The opinions expressed herein are those of the authors and do not necessarilyreflect the views of the Endeavour F ellowship Programme. The authors express theirgratitude to all farmers those have given a lot of valuable information without which thestudy could not have been realised.

References

1. BRKB. (2006). Rice statistics in Bangladesh. Bangladesh Rice Knowledge Bank, Bangladesh Rice Research Institute,Gazipur, Bangladesh.

2. DO F . (2007). F ishery statistical yearbook of Bangladesh 2005-2006. F isheries Resources Survey System, Department of F isheries, Dhaka, Bangladesh.


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3. Dewan, S. (1992). Rice-fish farming systems in Bangladesh: past, present and future. In: Rice- F ish Research andDevelopment in Asia (eds. C.R. dela Cruz, C. Lightfoot, B.A. Costa-Pierce, V.R. Carangal and M.P. Bimbao), ICLARMConference Proceedings 24:11-17.

4. Wahab, M.A., Kunda, M., Azim, M.E., Dewan, S. and Thilsted, S.H. (2008). Evaluation of freshwater prawn-small fishculture concurrently with rice in Bangladesh. Aquaculture Research 39:1524-1532.

5. F rei, M. and Becker, K. (2005). Integrated rice-fish culture: coupled production saves resources. Natural ResourcesF

orum 29:135-143.

6. Lightfoot C., dela Cruz, C.R. and Carangal, V.R. (1990). International research collaboration in rice-fish research. NAGA,the ICLARM Quarterly 13:12-13.

7. Harun, A.K.Y and Pittman, K.A. (1997). Rice-fish culture: feeding, growth and yield of two size classes of Puntiusgonionotus Bleeker and Oreochromis spp. in Bangladesh. Aquaculture 154:261-281.

8. Nhan, D.K., Phong, L.T., Verdegem, M.J.C., Duong, L.T., Bosma, R.H. and Little, D.C. (2007). In tegrated freshwateraquaculture, crop and livestock production in the Mekong delta, Vietnam: determinants and the role of the pond.Agricultural Systems 94:445-458.

9. Nabi, R. (2008). Constraints to the adoption of rice-fish farming by smallholders in Bangladesh: a farming systemsanalysis. Aquaculture Economics and Management 12:145-153.

10. Berg, H. (2002). Rice monoculture and integrated rice-fish farming in the Mekong delta, Vietnam - economic andecological considerations. Ecological Economics 41:95-107.

11. Gupta, M.V., Sollows, J.D., Mazid, M.A., Rahman, A., Hussain, M.G. and Dey, M.M. (2002). Economics and adoptionpatterns of integrated rice-fish farming in Bangladesh. In: Rural Aquaculture (eds. P. Edwards, D.C. Little and H.Demaine), CABI Publishing, Oxford, UK, pp. 41-53.

12. Halwart, M. and Gupta, M.V. (2004). Culture of fish in rice fields. F AO and the World F ish Center, 83 p.

13. F AO. (2000). F orest resources of Bangladesh - country report. F orest Resources Assessment Programme, F orestryDepartment, F AO Working Paper 15, Rome, Italy.

14. Mustow, S.E. (2002). The effects of shading on phytoplankton photosynthesis in rice-fish fields in Bangladesh.Agriculture, Ecosystems and Environment 90:89-96.

15. Kunda, M., Azim, M.E., Wahab, M.A., Dewan, S., Roos, N. a nd Thilsted, S.H. (2008). Potential of mixed culture of freshwater prawn ( Macrobrachium rosenbergii ) and self recruiting small species mola ( Amblypharyngodon mola ) inrotational rice-fish/prawn culture systems in Bangladesh. Aquaculture Research 39:506-517.

16. Lu, J. and Li, X. (2006). Review of rice-fish-farming systems in China - one of the globally important ingeniousagricultural heritage systems (GIAHS). Aquaculture 260:106-113.

17. Mohanty, R.K., Verma, H.N. and Brahmanand, P.S. (2004). Performance evaluation of rice-fish integration system inrainfed medium and ecosystem. Aquaculture 23:125-135.

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